Electronic devices such as, for example, printed circuit boards (PCBs) generate heat due to the flow of electricity and the resistance thereto by components within the electronic device. The heat generated by the electronic device can diminish the performance and reliability of the electronic device. A conventional method of cooling higher heat level electronic devices is to couple the electronic device to a heat exchanger or cold wall which may be of the type shown in FIG. 1. Heat exchanger 80 includes a flow path 81 through which may flow a heat transfer fluid to absorb heat produced by an electronic device (not shown) which is coupled to heat exchanger 80. Heat exchanger 80 has an inlet 82 through which a heat transfer fluid is introduced into flow path 81 and an outlet 83 through which the heat transfer fluid exits flow path 81. As shown in the enlarged cross-sectional partial view 85, provided in FIG. 1, the flow path may comprise a plurality of channels 86 through which the heat transfer fluid flows.
For significantly higher heat loads a different type of heat transfer fluid or coolant may be required that absorbs heat by changing from a liquid to a vapor. These heat exchangers are sometimes referred to as two-phase cold walls. Referring to FIG. 1, with a two-phase cold wall the heat transfer fluid enters the heat exchanger 80 through inlet 82 as a liquid. After absorbing heat the heat transfer fluid becomes a vapor and exits the through outlet 83. Two phase heat exchangers are considerably more difficult to design for full performance due to the coexistence of liquid and vapor within the same flow passages. Also uneven distribution of the incoming liquid can result due to changing orientation or acceleration loading of the heat exchanger.